Electromagnetic device



' Jan.I 26, 1932.

J. ERICKSON 1,842,595

ELECTROMAGNETI DEVIQE original Filed oct. 24. 1927 Juhu Erzcksnn Patented Jan. 26, 1932 UNITED STATES PATENT oFrlcE JOHN ERICKSON, 0I" CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO

ASSOCIATED ELECTRIC LABORATORIES, INC., OF CHICAGO, ILLINOIS, A COBTOBA- 'non or DELAwAnE ELECTBOHAGNETIC DEVICE Application med October 24, 1927, Serial No. 228,126. Renewed February 27, 1980.

This invention relates in general to electromagnetic circuit closing devices, and more specifically to a. relay for controlling various circuits in electrical systems.

One of the objects of the invention is the construction of a relay of this type which is extremely sensitive and which will operate efficiently on very low values of input power.

Another object of the vinvention is to provide a relay for use in tele hone systems or power systems, which is a apted to operate its armature eiliciently at'a very high rate of speed when either alternating or direct current is connected to the windings of the relay.

Another object is to provide a relay having a laminated core constructed of one sheet of soft magnetic iron continuously bent and folded into layers to the proper shape so as to reduce the eddy currents generated in the core when a source of current is connected to the relay and it is energized.

A further object is the provision of a relay having an adjustable armature which will respond accurately to very light energizations of the relay and control various circuits.

@ther objects and features of the invention will become apparent by a perusal of the detailed description and drawings in which:

Fig.` 1 is a full size end or front view of a preferred embodiment of the improved relay.

Fig. 2 is a top view of the relay shown in Fig. 1. A

Fig. 3 is a side view of Fig. 2 taken from the right side of this figure.

Fig. i is a bottom view of the armature which is shown as a top view in Fig. 2.,

Fig. 5 is a perspective view of a completely assembled core of the relay, enlarged several L-shaped magnetic metal heel piece 5, the bottom portion of which is substantially thicker than the other part. This-bottom portion has two holes into which the laminated cores 8 of the coils 6 and 7 are fastened by means of screws 23 and 24. Upon the upper end of the heel piece 5 are two small b ent over portions upon which the two extensions 16 and 17 of the part 10 are fastened by screws 14 and 15.

The armature9 consists of two parts, one part 10 comprising a thin sheet of non-magnetic spring metal having a number of extensions 13, 16, 17 and 18,' and the other part 9 which consists of a at piece of magnetic metal. The part 10 is fastened to the armature 9 by screws 32 and 19 on top. The

extensions 16 and 17 as has been stated, fasten to the heel piece 5 by the screws 14 and 15 and lie substantially in the same plane with the bottom edge of the armature 9 and on each side thereof. rlhe extensions 13 and 18 lie on top of the armature 9, with the extension 18 which has a Contact portion at its extremity, normally resting against an adjustable c'ontaot screw 11, and opposite a similar screw 12. These screws 11 and 12 are threaded into expanded terminal plates 30 and 31 which are fastened to andinsulated from the extensions 3 and 4 of the frame 2.

The armature 9 is fastened to the part 10 by screws 19 and 32, and the bottom edge of the armature rests Hat against the topl edge of the heel piece 5. An extension of the armature projects outward under the part 18 as best Iseen in Fig. 4. Fastened around the end of the extension 13 is one end of a coil spring 20, the other end of which is fastened'to an insulated bushing 29, which in turn is held on a il-shaped spring member 22. An adjusting bolt 21 is 'threaded through one end of the member 22, holding the coil spring 20 under constant tension, and the edge of the armature 9 against the top edge of the heel piece 5. In addition the contact portion of the extension 18 is held against the contact of the adjusting screw 11, by this spring 20.

It will'thus be seen that by turning the bolt 21 the tension applied to the armature 9 can be readily adjusted so that the armature can be balanced a slight 'amount on the heel piece against the contact screw 11, and

a very light energization of the coils-6 and 7 will ull the amature down against the cores 8. he two extensions 16 and 17 act as a resilient hinge for the amature 9 and the plvot point is on the front end of the armature where the extensions 16 and 17 are bent over and'join the portion 10.A The armature is ver easily moved vertically but cannot be shifted horizontally of its resting point on vthe heel piece 5, or the ccitact on the end of the extension 18 moved out. of ali ent with the contacts on the screws 11 an 12.

,When the armature 9 is attracted andthe contact portion of the extension 18 is iny engagement with the contact screw 12, the extension of the armature 9 lying below the extension 18 will be slightly parted at the end,

, 20 so that upon the deenergization of the coils this separation at this point, due to the tension stored in the extension 18, will assist the coil spring 20 in restoring the armature to normal, and in addition act as a residual to g5 prevent the armature from sticking to the cores. With this arrangement no chattering of the armature will result when alternatingl current is connected to the coils.

- The slots 26 in the heel piece 5 extending 30 outwardl from each core 8 revent eddy currents rom being generated 1n the bottom of the heel piece when the coils are ener 'zed, by interrupting their flow at ,the slots. imilarily the slots 27 and 28 in the armature 9, which extend midway towards the center of the cores 8, will prevent eddy current from forming on that part of the'armature adjacent to the cores. These slots materiall m crease the efficiency of the relay and ren er it more sensitive, so that no opposing magnetic forces will tend to hinder the satisfactory operation of the armature. Y The cores 8 of the relay, one of which extends through each coil 6 and 7 are made of a single sheet of soft magnetic iron bent and folded in the form shown in Figs. 5 and 6. The metal vis continuously bent and folded backward and forward into laminations which gradually increase in width towards the center of the' core and then decrease to the end. The core is then suitably compressed into a round shape as shown in Fig. 5. The folds orv layers of the laminations extend lengthwise of the core and the edgesare on each end of the core. The iirst fold is bent over on itself and each succeeding fold is made slightly wider till the mid point of the core is reached. Then the folds are gradually made narrower untill the end. This is so that when the folds are compressed by app plying pressure on the first and last fold, or

in other wordsthe ends of the folded sheet on the outside of the core, they will naturally "'F assume a cylindrical shape and no further Luanco bending. or compressing is n me. to make the core round.

With this completed form of the core the eddy current losses incurred when the relay is energized are considerably reduced and the relay will operate its armature quickly when energized and release it faster when deenergized. The folds of the core are small enou h that should eddy currents form they can o y take place at the point on theend where the metal is folded back onto itself, and these current losses will be so insignificant as ,to have practically no effect on the operation of the armature or relay. Consequently very weak currents connected to the relay will operate it in a reliable manner.

This above is a preferred method of making the laminated core, but a modification of this consists in taking two sheets of soft magnetic iron, of lthe same size, with their fiat surfaces adjacent one another and then continuously bending and folding them in the manner above described in connection with a single sheet of iron. This construction will have the same effect on eddy currents as -the single sheet.

en a source, of vcurrent is connected to the windings of coils 6 and 7 a magnetic flux is set up over a path comprising the cores 8 of each coil, the heel piece 5, throu h the armature9 and across the air gap to t e end of the cores 8'. As the part 10 is made of non-magnetic met-al no flux flows through it. The armature 9 is operated quickly and moves down upon the cores 8, against the tension of the coil spring 20, and rocking on the upper end of the heel piece 5 against which it is'held by the spring 20 and hinged to the heel piece by the resilient extensions 16 and 17. In addition the extension 18, having the contact point at its end, follows the armature and is moved by it away from contact screw 11 and in engagement with conios tact screw 12. The armature continues its downward movement until it strikes against the ends of the cores 8. As the extension 18 is arrested by the contact screw 12 it will be slightly separated from the armature, the distance increasing outward from where this extension is attached to the armature lby screw 19. When the coils are deenergized and the magnetic ilux ceases to flow the arma; ture is returned quickly to its normal position by the energy stored in the coil sprlng 2O and also, at the beginning of its return movement, by the spring like action of the extension 18 against contact screw 12, which will assist in preventing the armature from sticking against the cores due .to the slight reluctance of the magnetic flux.

A soldering tag is placed under the screw 14 so as to. complete the electrical circuit through-the extensions 17 and 18 to the contact point at the end thereof. For this reason the bushing 29 is made of insulation material and the bottom of the heel piece 5 is insulated from the frame 2 by a sheet of insulation; The expanded terminalplates 30 and 3l, which are insulated from the extension 3 and 4 oft-he frame 2, have soldering tags to complete the. circuit to the contact screws 11 and 12. y

In Fig.`7 a schematic circuit diagram is illustrated, showing one application of the.

improved relay, for example, in a telephone system. An incoming line 40, 41 from a dis tant exchange terminates in the primary winding of the repeating coil 42. The secondary winding goes through both coils 6 and 7 of the relay in series, with a con denser 43 in shunt of the coil 7 It will be noted that coil 7 is placed to the right of coil 6 in the drawing,y whereas it actually is be hind this coil, the drawing being made in this manner merely for the sake of clearness. The armature 9 has a source of battery connected to it and the contacts 1l and 12 are attached to wires leading to well known types of automatic switches which establish connection with a called telephone under control of a calling device at a telephone in the distant exchange. It is presumed that dialing takes place with alternating current-feed over the line conductors 40 and' 4l.4 The coils 6 and 7 respond to the interruptions produced in the line by the dial and alternately make and break the contacts 11 and 12 to operate the automatic switches. Ordinarily a relay of this type would chatter with the cycles of the alternating current, or if the line from the distant exchange were exceedingly long would not follow the weak current interruptions accurately. The condenser 43 is therefore inserted around coil 7, so that coil 6 will be slightly out of Yphase with coil 7 and therefore prevent chattering. lVith the laminated cores of the coils which reduce eddy currents, and the slots 26 in the' heel piece 5, and also slots 27 and 28 in the armature which also reduce eddy currents, the relay will respond to very weak currents accurately and as fast as desirable.

Another adaption of the relay is in circuits employing audion tubes, in which the relay isl connected in the plate circuit ofthe tubes, and is operated by the amplifying current to control various local circuits as desired.

Numerous other applica-tions for the relay -are readily apparent to any one skilled in the art, and it is not desired to be limited to the precise structure illustrated and described, but only by the scope of the appended claimsl wherein the various novel features are pointed out.

lVhat is claimed is:

l. In a sensitive relay, a heel piece, a pair of coils having laminated cores mounted on one end of said heel piece, an armature resting against the other end of said heel piece,

a spring member having extensions and attached to the top of said armature, oneextension having a contact portion and another extension having spring retaining means for holding said armature on the end of said heel piece, and additional extensions of said spring member arranged on each side of said armature for pivoting said armature and holding it in position.

2. ln a relay, a heel piece, a pair of coils having continuous laminated cores mounted on one end of said heel piece, an armature having one edge lying on top of the upper end of said heel piece and held thereto by a coil spring, a spring member attached to the top surface of said armature, a resilient contact making extension on said member, and additional extensions on said member arranged on each side of and bent on thelsame plane with the lower surface of said armature, the ends of said last members being attached to said heel piece so as to hold said armature in position and form a pivot point therefor when said armature is attracted.

3. in a sensitive relay, a pair of coils having laminated cores fastened to one end of an iron heel piece, an armature lying on the upper end of said heel piece and held in position thereon by a spring member having a plurality of extensions, two of which are arranged on each side of the armature and in the same plane with the lower surface of said armature and two others arranged on the top surface, one of said last extensions having means for adj ustably holding said armature on said heel piece and the other having contact means at its extremity for controlling an electrical circuit. l

4. In a sensitive relay, a pair of coils having laminated cores fastened to one end of an iron heel piece, slots 4in said heel piece extending outwardly from said cores, an armature vattached to the upper end of said heel piece by extensions on a spring from opposite the center of said cores, and means 1ncluding said slots for minimizing the generation of eddy currents in said heel piece and armature when said relay is energized.

5. An electromagnet having a pair of laminated cores, a heel piece supporting one end of said cores, an armature on the opposite end of said cores, a trident-shaped spring member for supporting said armature having two outer extensions bent back and secured to said heel pieceand the centerextension secured to an armalture-tensioning` spring, and another extension on said spring member forming a contact member movable between contact studs for controlling electrical circuits.

6. An electromagnet havinga pair of laminated cores, a heel piece attached to one end of said cores, an armature positioned opposite the other end of said cores, a spring member attached to one end of said heel piece and acting as the sole support for said armature,

:usl

and a plm ality of extensions on said spring member arranged to ivot said armature on said heel piece and to exibly hold said armature on its front edges so that said armature is free to rock in one plane and rigidly held A. from lateral movement in another plane.

In witness whereof, I hereunto subscribe my name this 21st day of October, A. D. 1927.

JOHN ERICKSON. 

